Calipering method and apparatus



1955 R. F. MONTGOMERY AL 2,719,361

CALIPERING METHOD AND APPARATUS 5 Sheets-Sheet 1 Filed Nov. 5, 1952 IN V EN TOR 0 it u I III. I'l il l llillrJll i I Oct. 4, 1955 R. F. MONTGOMERY ETAL 2,

CALIPERING METHOD AND APPARATUS 5 Sheets-Sheet 2 Filed Nov] 5, 1952 @2149 g M 7 mm QM/4.1a. BY 2 7 ATTORNEYS Oct. 4, 1955 F, MONTGOMERY ETAL. 2,719,361

CALIPERING METHOD AND APPARATUS Filed NOV- 5, 1952 5 Sheets-Sheet 3 IN ENTOR ATTORNEYS Oct. 4, 1955 R. F. MONTGOMERY L 2, ,3

CALIPERING METHOD AND APPARATUS 5 Sheets-Sheet 4 Filed NOV. 5, 1952 I NVENTOR ATTORNEYS 1955 R. F. MONTGOMERY ETAL 2,719,351

CALIPERING METHOD AND APPARATUS 5 Sheets-Sheet 5 Filed Nov. 5, 1952 INVENTOR United States Patent CALIPERTNG METHOD AND APPARATUS Richard Franklin Montgomery, Snyder, and Nicoiaas Leonardus Huibertus Koot, Odessa, Tex.

Application November 5, 1952, Serial No. 318,826

23 Claims. (Cl. 33--178) Our invention relates to the art of calipering a well bore, and more specifically provides a novel method of running the caliper and novel apparatus for carrying out said method.

The principal object of our invention is to provide a novel and greatly improved method of running a caliper within a drilled bore. It is well known that the removal of a drill string from a bore several miles deep is a timeconsuming operation which in itself contributes relatively little information to the operators. In all known methods now used, when the bore is completed it is necessary to pull all of the drill string out of the bore and then to run a caliper down into the bore on a wire line, the log generally being recorded on the surface by the aid of electronics. According to the present invention, however, a special section of pipe, hereinafter referred to as the substitute, is inserted between the drill bit and the lowermost drill collar prior to the beginning of the drilling operation. When this operation has been completed and the desired depth of bore established, the operator then opens the Kelly joint and inserts our novel recording tool into the pipe string and pumps the recording tool downwardly in the string until it reaches and enters the substitute. The arrival of the recording tool in the bore of the substitute triggers a latch metchanism thereby releasing a plurality of caliper arms to pivot outwardly and engage the walls of the bore, the recording tool automatically being oriented with said arms and latched in proper engagement therewith. When the recording tool is thus operatively engaged with the caliper arms, the tool will record a running log of the size of the bore as the substitute and drill string assembly is moved upwardly within the bore during removal of the drill string therefrom. When the assembly has thus been withdrawn, the recording tool is recovered from within the substitute and the operator removes the chart whereon is graphically inscribed the running log of the diameter of the bore.

An important feature of novelty of our invention relates to the above mentioned pumping of the recording tool downwardly through the drill string whereby said tool travels in a smooth bore all the way down to the substitute. This feature eliminates the possibility of the tool sticking or getting lodged or hung up as it travels downwardly. The tools of the prior art when lowered on a wire line into the bore have a tendency to encounter irregularities within the bore and bridge thereacross, particularly when the bore drilled into the earth is not straight.

Another important object of our invention is to provide an engagement between the substitute and the recording tool having an annular clearance to establish fluid passage ways so that when the recording tool is latched within the substitute fluid circulation may be maintained through the pipe string to enable the operator to maintain control of the bore against blowouts.

Another important object of our invention is to provide a substitute having two telescoping barrel sections,

ICE

the inner section normally being retracted within the outer section, and the sections being provided with splines or intermeshing tooth-engagements so as to prevent relative rotation therebetween during the drilling of the bore. When the recording tool is pumped downwardly into the substitute, the inner barrel section is released to telescope outwardly of the outer barrel section, the caliper arms being recessed in slots within the inner barrel section when the two sections are telescoped together, but pivoting outwardly of the inner barrel section as the latter telescopes downwardly with respect to the outer barrel section. When the two barrel sections are in their elongated position, the engagement therebetween is changed from a non-rotatable spline engagement. to a ball-bearing engagement so as to permit the outer and inner barrel sections to freely rotate with respect to each other. The advantage of this change of engagement from non-rotatable to rotatable is that when the two barrel sections are in their mutually elongated position and the caliper arms are engaging the walls of the bore, the pipe string may be rotated by the operator for the purpose of disconnecting the stands of pipe as they are withdrawn from the bore, thereby allowing the caliper arms to stand motionless against the well bore while the pipe string is being rotated to disconnect a stand.

Another important object of our invention is to provide each arm with telescoping lengths whereby the arms will not be damaged in the event the pipe string should be lowered through a short distance as the pipe joints are unscrewed at the surface during removal of the successive stands of pipe.

Another primary object of our invention is to provide an hydraulic recording tool adapted to be latched within the elongated substitute and having a plurality of cam surfaces each of which engages one or more of the caliper arms, said cam surfaces being moved by said arms in accordance with the variation of the pivotal position of the arms as they travel upwardly within the bore constantly contacting the varying inside diameter thereof. Each of these cams is operatively connected to a measuring piston acting upon a confined liquid within the recording tool. The total volume of space occupied by the confined liquid is always constant and the respective measuring pistons, as they are moved by the associated cams, cause the distribution of the fluid on each side of a separate recording piston to fluctuate, thereby driving the recording piston upwardly or downwardly within the recording tool in accordance with the instantaneous summation of the positions of all of the measuring pistons. The recording piston is linked to a recording stylus, which stylus presses against a moving chart and records thereon the average diameter of the well bore in accordance with the summation of the readings supplied by all of the aforementioned caliper arms, the moving chart being drivenby a clock mechanism contained within the recording tool.

The advantage of this assembly is that the log of the diameter of the well bore may be accurately obtained because of the fact that the various caliper arms work independently of each other and because of the fact that the hydraulic recording system provides a reading which is proportional to the summation of the instantaneous positions of all of the arms. Thus, if the well bore is crooked and the caliper is lying against one side of the bore so that the caliper arms are fully retracted on that side, the arms opposite the side of the caliper contacting the well bore will be further expanded to compensate for the fact that the caliper is not centered within the bore at that particular moment.

Another important advantage of the present invention is that static-electric charges within the bore will not affect the readings of the recording tool, since the latter operates by mechanical and hydraulic means rather then by electrical recording means.

Other objects and advantages of our invention will become apparent during the discussion of the drawings, wherein:

Fig. l is a section through a well bore, showing a drill string including the aforementioned substitute interposed in the drill string adjacent the drill bit, the substitute being in telescopic retracted position.

Fig. 2 is a section through the well bore, showing the drill string pulled upwardly through a distance sufficient to-permit the inner barrel section of the substitute to elongate downwardly with respect to the outer barrel section and showing the caliper arms extended outwardly and engaging the walls of the bore.

Figs. 3 and 3a illustrate a longitudinal section through the substitute, showing the inner barrel section retracted and latched Within the outer barrel section, and showing the drill bit operatively engaged therewith.

Figs. 4 and 4a illustrate a longitudinal section through the recording tool, showing the measuring cams connected with the measuring pistons, and showing the chart drums operatively engaged with the clock and drive mechanism, the latter being illustrated only schematically.

Figs. 5 and 5a illustrate another longitudinal section through the recording tool, showing a clear illustration of the chart drive and stylus means.

Fig. 6 is a longitudinal section through the substitute, showing the respective inner and outer barrel sections retracted, and showing the recording tool in a location just prior to the position in which it triggers the latch holding the inner barrel section retracted within the outer barrel section.

Fig. 7 is a longitudinal section through the substitute, showing the inner barrel section in elongated position with respect to the outer barrel section, and showing the recording tool latched within the inner barrel section and operatively associated with the extended caliper arms.

Fig. 8 is an enlarged section view taken along line 8-8, of Fig. 6.

Fig. 9 is an enlarged section view taken along line 99 of Fig. 3.

Fig. 10 is an enlarged section view taken along line 1010 of Fig. 2.

Fig. 11 is a section view along line 1111 of Fig. 5a.

Fig. 12 is a section view along line 12 12 of Fig. 4a.

Fig. 13 is a section View along line 13-13 of Fig. 4a.

Fig. 14 is a section view along line 1414 of Fig. 40.

Fig. 15 is a section view along line 1515 of Fig. 5.

Fig. 16 is a section view along line 1616 of Fig. 5.

Referring now to the drawings, Figs. 1, 2 and 7 illustrate the drilling and calipering assembly within the bore B, Figs. 1 and 2 illustrating a drill string S having a drill bit D at the bottom thereof and having interposed within the string directly above the bit D the telescoping and rotating substitue 1.

The substitute By reference to Figs. 3, 3a, 6 and 7 it will be seen that the substitute 1 includes an outer barrel section 2 and a telescoping inner barrel section 3. The respective barrel sections 2 and 3, when in their mutually retracted position, engage each other non-rotatively at the splines 2a and 3a, and also engage each other at the intermeshing teeth 2b and 3b, the splines and teeth being provided so as to permit transmittal of torque from the drill string S through the substitute to the drill bits D during drilling operation. The outer and inner barrel sections are maintained in their mutually retracted position by the latches 3c which engage the annular shoulder 2c, said latches being yieldably maintained in engagement with the shoulder 26 by the leaf springs 3d and said latches having at their lower ends inward projections 3e, Fig. 3.

By reference to Figs. 3, 3a, 6 and 7 it may be seen that the inner barrel section 3 has an annular series of axially disposed slots 3 which slots normally house the caliper arms 4, the latter being pivotally supported in the slots near their upper ends by a set of pins 4a, Fig. 8. Each slot also contains a spring 4b secured to the inner barrel section 3 at the upper end of the slot 3f, each of which springs is secured at its lower end to a caliper arm at a point 40 below the pins 4a. It will be noted from the drawing that when the inner barrel 3 is retracted within the outer barrel 2, the caliper arms 4 are nested in the position shown in Fig. 6 and are protected from damage during the drilling operation by the outer barrel 2 which completely covers the arms 4. Each arm 4 telescopically receives a retractable extension 4a, which extension is normally pressed outwardly by the springs 4:2, as shown in Fig. 3, and the extensions 4d terminate at their outer ends in rounded feeler members 4f, which members engage the walls of the bore and are moved inwardly and outwardly with respect to the inner barrel 3 as the latter is drawn upwardly within the said bore during withdrawal of the pipe string.

By reference to Figs. 3, 6, 7 and 9 it will be seen that the inner barrel 3 has mounted near its upper end a series of ball bearings 5, which ball bearings are inoperative when the outer and inner barrel members 2 and 3 are in mutually retracted position but which ball bearings engage the annular shoulder 2d when the outer and inner barrels 2 and 3 are in their extended positions as shown in Fig. 7, the ball bearings being more clearly shown in Fig. 9. When the inner and outer barrel members 2 and 3 are in extended position the splines 2a3a and the teeth 2b3b are disengaged so that the inner barrel 3 may freely rotate within the outer barrel 2, the former being vertically supported by the latter through the engagement of the ball bearings 5 with the annular shoulder 2d, thereby permitting the inner barrel section 3 and associated arms 4 to freely rotate with respect to the outer barrel 2 and associated pipe string S.

The recording tool When the drill string and drill bit have reached the depth required for the bore, the Kelly joint (not shown) is opened and the recording tool 6 is inserted into the drill string. The operator then starts the pump and pumps the recording tool 6 downwardly within the string S. At the instant before the recording tool 6 triggers the latch 30 to release the inner barrel member 3 to drop downwardly with respect to the outer barrel member 2, the various parts of our caliper are in the position shown in Fig. 6.

At the lower end of the recording tool 6 is a centralizer 6a adapted to insure that the recording tool 6 will travel freely into the tubular center 3g of the inner barrel section 3, it being noted that at the upper end of the tubular center 3g is a conically tapered entrance 3h adapted to direct the centralizer 6a into the tubular center 3g. As the recording tool 6 progresses downwardly within the tubular center 3g the lower end of the recording tool 6 contacts the internally extending projections 32, thereby pushing the latter outwardly and releasing the latch 30 from the annular shoulder 20. The inner barrel portion 3 is thereby permitted to elongate downwardly, as shown in Fig. 7, and upon further application of pumping pressure from above the recording tool 6 is forced downwardly until the annular groove 6b is latched by the projections Be, at which time the recording tool 6 is operatively associated with the caliper arms 4.

The upper end of the recording tool 6 is provided with outwardly extending bosses 60, which bosses engage the conical entrance 3h, thereby preventing further downward movement of the recording tool 6. The upper end of the recording tool 6 may also be provided with a fishing tip 6d to facilitate removal of the tool 6 from the pipe string, if such removal should be desired at any time before the projections 32 latch into the groove 6b.

By reference to Figs. 4, 4a, 5 and 5a, 6 and 7 will be seen that at the lower end of the recording tool 6 are a series of downwardly extending cam surfaces 7, these surfaces being shown in end view in Fig. 14. Above the cam surfaces 7 and integral therewith are measuring pistons 7a, each of the pistons 7a having an upwardly extending connecting rod 7b screwed into an upper measuring piston 70, each of the connecting rods 7b extending through a sleeve 8 secured against longitudinal displacement by means of a set screw 8a. Above each measuring piston 7c is a compressed coil spring 9, which spring operates to press the associated piston 7c downwardly within its associated cylinder 6e, which cylinder is vented outside of the body of the recording tool 6 as at the vent 6 1 By reference to Figs. 12 and 13 it will be seen that each of the cylinders 62 is connected together by two different sets of ducts, the space between the sleeve 8 and the upper cylinder 7c being connected to an axial duct 6g by a set of short ducts 6h, Fig. 12.

By reference to Fig. 13 it will be seen that the space within the cylinder 6e and lying between the sleeve 8 and the lower measuring piston 7a is connected with the longitudinal duct 6k by means of a plurality of short ducts 6m.

By reference to Figs. 5 and 5a it will be seen that the cylinders 6e and the ducts 6g, 6h, 6k, and 6m are filled with a liquid, and that this liquid presses against the lower end of a recording piston 10 in duct 6k, and that the liquid also presses against the upper end of the recording piston 10 as at 6r, Fig. 5.

It should now be apparent that when a cam 7 is moved upwardly, the volume below the associated piston 7c (and therefore the volume of liquid within the ducts 6g and 6r) will increase and that by the same movement the volume of liquid within the cylinder above the piston 7a (and therefore in the ducts 6m and 6k) will decrease so that the liquid will press against the lower end of the recording piston 10 and move it upwardly. Conversely, when the cam surface 7 is moved downwardly the liquid will press against the upper end of the recording piston 11) and drive the latter downwardly.

Figs. 12 and 13 show that all of the cylinders are connected together both in the vicinity of the ducts 6h and in the vicinity of the ducts 6m, and therefore the amount of motion transmitted to the recording piston 10 by the liquid will be proportional to the instantaneous summation of the movement up or down of all of the cams 7.

At the upper end of this system of ducts, Fig. 5, is a plug 11 adapted to confine the liquid within the ducts and having a screw 11a through which the liquid may be replenished and through which air may be removed from within the ducts. The plug 11 also has a bore 11b through which a hollow recording shaft 12 passes, the shaft being attached at its lower end to the recording piston 10 and carrying at its upper end a recording stylus 12a. This shaft also has a small breather port 12b communicating through the center of the shaft 12 with a duct 10a so as to vent the chamber 10b, which chamber is normally free of liquid.

The chart chamber 6s houses the data-recording mecha nism and has an access door 6p to permit installation or removal of the charts C from the chart rollers 13 and 13a. It will be noted in Fig. 15 that the chart C travels from the roller 13 around the idler rollers 13c and 13d and on to the takeup roller 13a, the stylus 12a recording the various positions at any particular instant of time by marking the chart C against the idler roller 130, the stylus being at all times spring-loaded by the leaf spring 12d.

A groove 6x is provided in the door 6p and supports the upper end 12c of the shaft 12, Fig. 15. A rubber roller 14 is supported on bearings 14:: fixed to leaf springs 14b which springs force the rubber roller 14 against the chart rollers 1313a. The rubber roller 14 is driven through a flexible cable 140, which in turn Operation In calipering the diameter variations of a bore B, the operator places the rotating and telescoping substitute 1 in the pipe string S directly above the drill bit D, the inner barrel portion 3 being telescoped upwardly into the outer barrel portion 2 and latched therein by the latch 30, at which time the splines 2a-3a and teeth Zia-3h mutually intermesh to prevent relative rotation between the barrels 2 and 3. With this assembly in the pipe string, the operator proceeds to drill the bore B into the earth, and when he has drilled the bore to its desired depth he retracts the drill string upwardly a few feet from the bottom of the bore B, opens the Kelly joint and inserts the recording tool 6 into the pipe string. He then closes the Kelly joint and starts the pumps to pump the recording tool 6 downwardly within the pipe string S so that the recording tool 6 arrives in the relative position shown in Fig. 6.

Upon continued pumping the recording tool 6 will proceed downwardly and into the tubular center 3g of the inner barrel section 3, at which time the lower end of the recording tool 6 will trip the projections 3e and release the latches 3c, thereby permitting the inner barrel portion to drop downwardly with respect to the outer barrel portion 2 until the ball bearings 5 rest upon the annular shoulder 2d. Continued pumping will force the recording tool 6 further downwardly within the tubular center 3g of the lower barrel 3 so that the projections.

3e will latch into the groove 6b, at which time the bosses 6c at the upper end of the recording tool 6 will be fitted snugly against the conical surface 3h, the bosses 6c and the projections 3e rigidly maintaining the recording tool 6 longitudinally positioned as shown in Fig. 7.

The upper end of the tool 6 is provided with guide grooves 6y, as shown in Figs. 6 and 7, which guide contacts the spring fingers 3y, shown in Fig. 3 only, at the upper end of the inner barrel portion 3 so that as the guide grooves 6y proceed downwardly with respect to the spring fingers 3y the recording tool body will be rotated until the cams 7 at the lower end thereof are properly aligned with the upper ends of the caliper arms 4. It will be seen by reference to Figs. 8 and 14 that in the present form there are six caliper arms 4 but only three cams 7, it being intended that in the present embodiment each cam 7 should accommodate the upper ends of two adjacent caliper arms 4.

When the recording tool 6 thus seats within the inner barrel portion 3, the operator will be informed of the fact by a rise in pressure as the tool 6 first enters the inner barrel portion 3 and by a drop in pressure as the tool 6 releases the latches 3c and the inner barrel 3 elongates with respect to the outer barrel 2. The operator then commences withdrawal of the pipe string from the bore. Generally the string will be withdrawn in stands of approximately three lengths of pipe each, and as the string is withdrawn upwardly the feeler members 4f on the lower ends of the caliper arms 4 will be moved inwardly and outwardly according to the various diameters of bore B encountered. The inward and outward pivoting of the arms 4 causes axial upward or downward motion of the cams 7 and the associated pistons 7a and 70. Axial fluctuation of the location of these pistons causes the volume of liquid within the respective ducts 6g and 6k to fluctuate in accordance with the instantaneous summation of the displacement of each of the three groups of pistons, thereby driving the recording piston 10, shaft 12 and stylus 12a upwardly and downwardly with respect to the chart C.

As stated above, the chart is moved by the chart rollers 13 and 13a, rotated at a constant rate by the clock mechanism 15; and as the drill string is removed, stand by stand, the chart C will show the summation ofthe instantaneous deflections of the various caliper arms 4.

Moreover, each time that the upward travel of the drill string is interrupted for the purpose of unscrewing a stand of pipe, the chart C will indicate a straight line during the interval that the stand is being unscrewed, since the caliper arms 4 will be standing still with respect to the walls of the bore at that time.

The arms 4 are provided with telescoping extensions 4d, Fig. 3, so that as the tool joints are unscrewed and the drill string according lowered in the bore by the length of the threads on the tool joints, the sections 4d may telescope within the sections 4 of the caliper arms to prevent bending or breaking thereof. As pointed out above, the pipe string S and associated outer barrel portion 2 may be rotated with respect to the inner barrel portion 3, which inner portion is supported from above only by the ball bearings 5 on the shoulder 2d. Thus as the pipe string is rotated the caliper arms stand still within the bore, thereby preventing damage thereto.

By inspection of Figs. 6 and 7 it will be apparent that the outer periphery of the recording tool 6 is spaced from the tubular center 3g of the inner barrel portion 3, thereby permitting circulation of the drilling mud between said two members at all times so that the operator will have sufficient control to prevent blowouts.

When the drill string has been entirely removed from the well the marked chart may be removed from the tool 6 and may be replaced by a new chart simply by unscrewing the upper casing 614 from the lower casing 6v of the recording tool 6 and by opening the door 6p which leads into the chart chamber, Fig. 5.

' We do not limit our invention to the exact form shown in the drawings, for obviously changes may be made therein within the scope of the claims.

We claim:

1. In a drill string terminating at its lower end in a bit for drilling a bore, a caliper assembly comprising an outer barrel section supported by said string; an inner barrel section telescopically engaged with said outer barrel section and supporting said bit, said barrel sections each having a liquid passage therethrough; complementary projections carried by said respective barrel sections and meshing when the latter are in mutually retracted position, said meshed projections transmitting torque from said string to said bit during drilling operations; latch means for maintaining said barrels mutually retracted, said latch means having a tripping member extending into said liquid passage; a plurality of axially I disposed annularly spaced caliper arms pivoted near their upper ends to said inner barrel and having cam engaging surfaces at their upper ends, said outer barrel sheathing said arms when said barrels are retracted; spring means yieldably urging said caliper arms outwardly with respect to said inner barrel; and a measuring and recording tool having a plurality of cams operatively associated with measurement recording means, said tool being pumped downwardly in said string when the drilling operation is concluded and tripping said latch to permit elongation of said telescoping barrels, said tool lodging in said inner barrel with said cams contacting said cam engaging surfaces on said arms, the latter being unsheathed in the elongated position of said barrels with their lower ends engaging the walls of said drilled bore, whereby upon upward withdrawal of said string and caliper assembly said arms will measure the diameter of said bore and transmit said measurements through said cams to said recording means.

2. In a device as set forth in claim 1, said measuring and recording tool having an annular groove around its periphery and having outstanding annularly spaced bosses around its upper end; said inner barrel having a conically flared mouth at the upper end of its liquid passage; centralizer means on said tool to smoothly guide the latter into said liquid passage; catch means in said liquid passage to lock in said annular groove and prevent upward withdrawal of said tool, said bosses engaging said flared mouth to arrest downward movement of said tool; and orienting means for turning the tool as it enters said liquid passage to align said cams with said arms, said tool being smaller in diameter than said liquid passage to permit liquid circulation to be maintained at all times through the drill string.

3. In a device as set forth in claim 1, said inner barrel having an annular series of axially disposed slots each housing an arm when said barrels are in retracted position, said arms each comprising two telescoping lengths; means to yieldably maintain said lengths elongated; and antifriction bearing means carried by said barrel sections and operatively engaging when the latter are in elongated position, whereby said supporting string and associated outer barrel can be freely rotated with respect to said inner barrel and associated arms engaging the bore, said telescoping lengths permitting the drill string to be lowered in the bore through short distances during withdrawal therefrom without damage to said arms.

4. In a device as set forth in claim 1, said measuring and recording tool comprising, a body having a plurality of. cylindrical bores extending thereinto, one of said cams being located at the opening of each cylindrical bore; a measuring piston in each cylindrical bore connected for unitary axial motion with each associated cam, each measuring piston dividing each cylindrical bore into upper and lower portions and the upper portions and the lower portions being respectively interconnected by upper and lower ducts; means for yieldably urging said measuring pistons outwardly in said cylindrical bores; a recording piston movably mounted in a recording cylinder, said upper ducts communicating with the upper end of said recording cylinder and said lower ducts communicating with the lower end of said recording cylinder; hydraulic liquid in said cylinders, ducts and cylindrical bores; a chart; means for mounting and driving the chart; and a recording stylus engaging said chart and linked to said recording piston, whereby as said cams and measuring pistons are moved axially of said cylindrical bores by the associated caliper arms the hydraulic liquid in said upper and lower ducts will be fluctuated to move the recording piston and associated stylus in proportion to the instantaneous average displacement of the said measuring pistons.

5. In a drill string terminating at its lower end in a bit for drilling a bore, a caliper assembly comprising inner and outer telescopically engaged barrels inserted in said string above said bit; said barrels each having a liquid passage therethrough; complementary projections carried by said respective barrels and meshing when the latter are in mutually retracted position to transmit torque from said string to said bit during drilling operations; releasable latch means for maintaining said barrels mutually retracted said latch means having a tripping member extending into said liquid passage; a plurality of caliper arms fixed to and retractable within said inner barrel and having tool engaging portions extending into the liquid passage when the arms are extended outwardly; spring means yieldably urging said caliper arms outwardly to engage said bore; and a recording tool to be lowered into said string when the drilling operation is concluded and trip said latch to permit elongation of said telescoping barrels, said tool lodging in said inner barrel and contacting said tool engaging portions of said arms, whereby upon upward withdrawal of said string and caliper assembly said arms will measure the diameter of said bore and transmit said measurements to said recording tool.

6. In a device as set forth in claim 5, said recording tool having an annular groove around its periphery and having an annular series of spaced bosses around its upper end; said inner barrel having a conically flared mouth at the upper end of its liquid passage; centralizer means on said tool to smoothly guide the latter into said liquid passage; catch means in said liquid passage to lock in said annular groove and prevent upward withdrawal of said tool, said bosses engaging said flared mouth to arrest downward movement of said tool, the latter being smaller in diameter than said liquid passage to permit liquid circulation to be maintained at all times through the drill string.

7. In a device as set forth in claim 5, said inner barrel having an annular series of axially disposed slots each housing an arm when said barrels are in retracted position, said arms each comprising two telescoping lengths; means to yieldably maintain said lengths elongated; and antifriction bearing means carried by said barrel sections and operatively engaging when the latter are in elongated position, whereby said supporting string and associated outer barrel can be freely rotated with respect to said inner barrel and associated arms engaging the bore, said telescoping lengths permitting the drill string to be lowered in the bore through short distances during withdrawal therefrom without damage to said arms.

8. In a device as set forth in claim 5, said recording tool comprising, a body having a plurality of cylindrical bores extending thereinto; an outwardly facing cam located at the opening of each cylindrical bore, said cams operatively engaging said caliper arms; a measuring piston in each cylindrical bore connected for unitary axial motion with each associated cam, each measuring piston dividing each cylindrical bore into upper and lower portions and the upper portions and the lower portions being respectively interconnected by upper and lower ducts; means for yieldably urging said measuring pistons outwardly in said cylindrical bores; a recording piston movably mounted in a recording cylinder, said upper ducts communicating with the upper end of said recording cylinder and said lower ducts communicating with the lower end of said recording cylinder; hydraulic liquid in said cylinders, ducts and cylindrical bores; a chart; means for mounting and driving the chart; and a recording stylus engaging said chart and linked to said recording piston, whereby as said cams and measuring pistons are moved axially of said cylindrical bores by the associated caliper arms the hydraulic liquid in said upper and lower ducts will be fluctuated to move the recording piston and associated stylus in proportion to the instantaneous average displacement of the said measuring pistons.

9. In a device as set forth in claim 8, spring finger means in the liquid passage of said inner barrel to engage a curved recess in the side of the tool; said engagement turning the tool as it enters said liquid passage to align saidcams with said arms.

10. In a drill string terminating at its lower end in a bit for drilling a bore, a caliper assembly comprising an outer barrel section supported by said string; an inner barrel section telescopically engaged with said outer barrel section and supporting said bit, said barrel sections each having a liquid passage therethrough and said inner barrel section having an annular series of spaced slots longitudinally disposed around its periphery; complementary projections carried by said respective barrel sections and meshing when the latter are in mutually retracted position, said meshed projections transmitting torque from said string to said bit during drilling operations; latch means for maintaining said barrels mutually retracted; said latch means having a trip member extending into said liquid passage; a caliper arm pivoted near its upper end in each slot, said arms being retractable within said slots and said outer barrel sheathing said arms when said barrels are retracted; spring means yieldably urging said caliper arms to pivot outwardly of said slots to contact the bore, said arms each having a tool engaging portion extending into the liquid passage when the arm is pivoted outwardly; and a recording tool to be lowered into said string when the drilling operation is concluded and trip said latch to permit elongation of said telescoping barrels, said tool lodging in said inner barrel and contacting said tool engaging portions of said arms, whereby upon upward withdrawal of said string and caliper assembly said arms will measure the diameter of said bore and transmit said measurements to said recording tool.

11. In a device as set forth in claim 10, said recording tool having an annular groove around its periphery and having an annular series of spaced bosses around its upper end; said inner barrel having a conically flared mouth at the upper end of its liquid passage; centralizer means on said tool to smoothly guide the latter into said liquid passage; catch means in said liquid passage to lock in said annular groove and prevent upward withdrawal of said tool, said bosses engaging said flared mouth to arrest downward movement of said tool.

12. In a device as set forth in claim 10, said arms each comprising two telescoping lengths; and means to yieldably maintain said lengths in an elongated condition, said telescoping lengths permitting the drill string to be lowered in the bore through short distances during withdrawal therefrom without damage to said arms.

13. In a device as set forth in claim 10, said tool being smaller in diameter than the liquid passage through the inner barrel to permit liquid circulation to be maintained at all times through the drill string.

14. In a device as set forth in claim 10, antifriction bearing means carried by said barrel sections and operatively engaging when the latter are in elongated position whereby said supporting string and associated outer barrel can be freely rotated with respect to said inner barrel and associated arms engaging the bore.

15. In a device as set forth in claim 10, said recording tool comprising, a body having a plurality of cylindrical bores extending thereinto; an outwardly facing cam located at the opening of each cylindrical bore; said cams operatively engaging said caliper arms; a measuring piston in each cylindrical bore connected for unitary axial motion with each associated cam, each measuring piston dividing each cylindrical bore into upper and lower portions and the upper portions and the lower portions being respectively interconnected by upper and lower ducts; means for yieldably urging said measuring pistons outwardly in said cylindrical bores; a recording piston movably mounted in a recording cyl inder, said upper ducts communicating with the upper end of said recording cylinder and said lower ducts communicating with the lower end of said recording cylinder; hydraulic liquid in said cylinders, ducts and cylindrical bores; a chart; means for mounting and driv ing the chart; and a recording stylus engaging said chart and linked to said recording piston, whereby as said cams and measuring pistons are moved axially of said cylindrical bores by the associated caliper arms the hydraulic liquid in said upper and lower ducts will be fluctuated to move the recording piston and associated stylus in proportion to the instantaneous average displacement of the said measuring pistons.

16. In a device as set forth in claim 15, spring finger means in the liquid passage of said inner barrel to engage a curved recess in the side of the tool, said engagement turning the tool as it enters said liquid passage to align said cams with said arms.

17. As an article of manufacture, a telescoping and rotating caliper assembly comprising, an outer barrel section; an inner barrel section telescopically engaged with said outer barrel section, said barrel sections each having a passage therethrough; and said inner barrel section having an annular series of spaced slots longitudinally disposed around its periphery; complementary projections carried by said respective barrel sections and meshing when said barrels are in mutually retracted position; latch means for maintaining said barrels mutually retracted; a caliper arm pivoted at its inner end in each slot, said arms being retractable within said slots and said outer barrel sheathing said arms when said barrels are retracted; spring means yieldably urging said caliper arms to pivot outwardly with respect to said slots; and antifriction bearing means carried by said barrel sections and operatively engaging when the latter are in elongated position, whereby said barrel sections may be freely rotated with respect to each other.

18. As an article of manufacture, a measuring and recording tool comprising, a body; a plurality of double acting measuring pistons, each movably housed in a cylinder in said body and connected for unitary axial motion with an externally located cam, said measuring pistons dividing each cylinder into upper and lower portions and being respectively interconnected by upper and lower ducts; a recording piston movably mounted in a recording cylinder, said upper ducts communicating with the upper end of said recording cylinder and said lower ducts communicating with the lower end of said recording cylinder; hydraulic liquid in said cylinders and ducts; means for mounting and driving a chart; and a recording stylus engaging said chart and linked to said recording piston, whereby as said cams are moved axially of said body the hydraulic liquid in said upper and lower ducts will be fluctuated to move the recording piston and associated stylus in proportion to the instantaneous average displacement of the said earns.

19. In a drill string, the combination of a caliper assembly comprising a barrel section, caliper arms pivoted to said barrel section in an annular series, each arm having a cam engaging portion extending into said barrel section, means for yieldably urging said arms to pivot outwardly, and releasable sheathing means to protect said arms during drilling operations; and a measuring and recording tool comprising a body, a plurality of cams movably carried by said body and contacting said cam engaging portions of said caliper arms, hydraulic piston means connected with said cams for averaging the instantaneous displacements thereof, a stylus linked with said hydraulic means to be moved thereby in proportion to said averaged displacement, and means for mounting and driving a recording chart in contact with said stylus.

20. The method of calipering a well bore at the conclusion of a drilling operation and during withdrawal of the drill string from the bore, including the steps of inserting in the drill string before the drilling operation a normally retracted caliper; and after completion of the drilling operation lowering a recording tool inside the drill string into the caliper; releasing the capiler to expand and contact the well bore; and withdrawing the drill string and caliper upwardly in the well bore while recording in the tool the calipered well diameters.

21. The method of calipering a well bore at the conclusion of a drilling operation and during withdrawal of the drill string from the bore, including the steps of inserting in the drill string before the drilling operation a normally sheathed calipering apparatus; and after completion of the drilling operation releasing from inside the drill string the calipering apparatus to unsheath the latter to expand and contact the well bore; and withdrawing the drill string and associated calipering apparatus upwardly of the bore while simultaneously calipering the bore.

22-. A calipering tool comprising a calipering sub adapted to be inserted in a drill string immediately above the drill bit, a plurality of normally retracted members pivotally mounted on said sub adapted to contact the well here when extended, means urging said wall contacting means toward their extended position, recording means adapted to be lowered through the well string into seating engagement with said sub, means on said recording means adapted to release said wall contacting members when said recording means seats in said sub, and means on said wall contacting members adapted to actuate said recording means.

23. In a drill string, a caliper assembly comprising an outer tubular member, an inner tubular member telescopicaly received in said outer member, means for connecting said outer member to a well string, means for connecting said inner member to a drill bit, means for preventing relative rotation between said members when said members are mutually retracted, latch means for releasably maintaining said members in said mutually retracted relation, a plurality of caliper arms pivoted to said inner member, said arms being shielded by said outer member 1' when said members are retracted, means urging said arms outwardly, recording means adapted to be lowered through said drill string, means on said recording means adapted to release said latch means, and means on said recording means adapted to contact said caliper arms and be actuated thereby, whereby upon withdrawal of said string and caliper assembly said arms will actuate said recording means to continuously record the well diameter.

References Cited in the file of this patent UNITED STATES PATENTS 1,981,665 Rieber Nov. 30, 1934 2,102,080 Kinley Dec. 14, 1937 2,232,360 Barnett Feb. 18, 1941 2,341,228 Moore Feb. 8, 1944 2,348,192 Chambers May 9, 1944 2,395,137 Millikan Feb. 19, 1946 2,524,031 Arps Oct. 3, 1950 2,567,548 Chaney et a1. Sept. 11, 1951 FOREIGN PATENTS 7,196 Great Britain Mar. 27, 1903 

